This proposal concerns mitotic spindle function in lysed mammalian tissue culture cells. Cells lysed early in anaphase into a mixture of polymerizable microtubule protein will continue to move chromosomes towards the spindle poles. This system will be used to characterize spindle biochemistry and to identify the enzymes responsible for chromosome movement. The steps required to reach this goal are: 1) development of a lysis protocol that maintains chromosome motion at consistent rates from one experiment to the next. Measurements of spindle mass, spindle birefringence and cytoplasmic density will be used as criteria for extent of lysis and extraction. 2) the enzymes responsible for chromosome movement will be identified by adding jamming proteins (proteins that bind the actin, myosin, dynein, etc.) or contractile proteins to perturb spindle function. The physiological requirements (ion cofactor, nucleotides, etc.) of chromosome movement will be established. This information should contribute significantly to our understanding of how mitosis works at a molecular level. BIBLIOGRAPHIC REFERENCES: Cande, W.Z., E. Lazarides, and J.R. McIntosh. 1977. A comparison of the distribution of actin and tubulin in the mammalian mitotic spindle as seen by indirect immunofluorescence. J. Cell Biol. 72: 552-567.